Mesh networks are composed of two or more electronic devices, each containing at least one transceiver. The electronic devices use their transceivers to communicate with one another and/or a central device. If the device wishes to communicate with another device that is out of transmission range, the device may communicate via multi-hop communication through other devices. In a frequency-hopping (or channel-hopping) mesh network, devices communicate using different frequencies/channels at different times. To communicate a packet, a transmitter-receiver pair must be configured to the same channel during packet transmission. For a transmitter to communicate with a receiver at an arbitrary time in the future, the transmitter and receiver must synchronize to a channel schedule that specifies what channel to communicate on at what time.
Channel schedules may be assigned to each transmitter-receiver pair independently so that neighboring transmitter-receiver pairs can communicate simultaneously on different channels. Such a strategy increases aggregate network capacity for unicast communication, but is inefficient for broadcast communication. Alternatively, all devices in a network may synchronize with a single channel schedule such that all devices transmit and receive on the same channel at any time. Such a strategy increases efficiency for broadcast communication since a single transmission can reach an arbitrary number of neighbors, but decreases aggregate network capacity for unicast communication since neighboring individual transmitter-receiver pairs cannot communicate simultaneously without interfering.
Existing systems optimize for both unicast and broadcast communication by synchronizing the entire network to the same channel-switching schedule and using a central coordinator to compute and configure channel schedules for each individual device. However, this method adds significant delay and communication overhead to coordinate new schedules between each transmitter-receiver pair. Other systems provide a hybrid approach, where the communication is divided between independently schedule unicast schedules and a shared broadcast transmission schedule.
Because the devices may rely on a small source of stored energy (e.g., batteries or a capacitor) during a power outage of a main power supply, only a limited lifespan of the backup power (e.g., battery or capacitor) may be used to transmit information. In particular, the Advanced Metering Infrastructure (AMI) application requires devices to communicate a Power Outage Notification (PON) when main-power is no longer available. Certain residential meters today currently store enough energy to allow for 30 seconds of uptime and 3 packet transmissions. Since a device does not know what neighbors are affected by the power outage event, it broadcasts the PON three times within the 30-second window. However, because a large number of spatially correlated devices may be affected by a single power outage event, significant congestion can occur due to PON transmissions. Note also that in the hybrid channel-hopping scheme mentioned above, the congestion of PONs may be exacerbated by only allowing broadcast communication for a faction of time.